1. Field of Invention
The present invention relates to a method for manufacturing an interconnect. More particularly, the present invention relates to a method for manufacturing a diffusion barrier layer to block copper atoms diffusing from the copper wires.
2. Description of Related Art
In the procedure for manufacturing an ultra large scale integration circuit, more than one hundred thousand transistors are disposed on a silicon surface with an area of only about 1 to 2 square centimeters. Additionally, in order to increase the integration of the integrated circuit, the density of the conductive wire used to electrically connect the transistors and the devices with each other are also increased. Therefore, in accord with the increased interconnects manufacturing requirements of miniaturized transistors, it is increasingly necessary for IC manufacturing to adopt a design with more than two metal layers. In particular, a number of multi-function products, such as microprocessors, even require 4 or 5 metal layers to complete the internal connections thereof.
With the decreasing size of the device, the distance between the adjacent conductive wires is decreased. In the extremely narrow space, unexpected capacitive and inductive coupling occurs between the parallel conductive wires and the capacitive and inductive coupling leads to interference between the conductive wires. Due to the interference between the conductive wires, the resistance-capacitance time delay (RC time delay) between the conductive wires is increased. The data transmission rate is especially repressed by the capacitive and inductive coupling when the data are to transmitted through the parallel conductive wires at a relatively high transmission rate. Hence, the energy waste is greatly increased and the efficiency of the device is limited.
Copper is currently the substitute of choice for aluminum interconnect material, because its high anti-electromigration and low resistance permit a decreased time delay of signal transmission Therefore, the resistance of the conductive wire can be decreased.
However, the use of copper as an interconnection material presents several problems. For example, copper oxidizes easily at low temperatures and copper diffuses easily into silicon dioxide and other dielectric materials used in micro-circuitry. Therefore, in order to overcome the disadvantages of using copper wires, it is necessary to passify surfaces of copper wires and provide diffusion barrier layers between copper and adjacent layers.
The invention provides a method of manufacturing a diffusion barrier layer. A substrate having a patterned copper layer formed thereon is provided. A surface of the patterned copper layer is converted into a copper-containing implantation layer.
The step of converting the surface of the patterned copper layer comprises a step of performing an implantation process to introduce a plurality of atoms into the surface of the patterned copper layer. Additionally, the atoms introduced into the surface of the patterned copper layer include oxygen atoms, nitrogen atoms or a mixture of atoms comprising oxygen atoms and nitrogen atoms.
Because of the formation of the copper-containing implantation layer, the copper atoms of the patterned copper layer can be blocked by the copper-containing implantation layer. Additionally, the dosage of the atoms introduced into the patterned copper layer by the implantation process can be controlled.
The invention also provides a method for manufacturing a diffusion barrier layer over a substrate having a patterned copper layer. A refractory metal layer is formed on the substrate and a top surface and a sidewall of the patterned copper layer. The refractory metal layer is converted into an oxygen-containing implantation layer as a diffusion barrier layer. A thermal process is performed to stabilize a diffusion barrier quality of the oxygen-containing implantation layer.
As embodied and broadly described herein, the step of converting the refractory metal layer into the oxygen-containing implantation layer includes an implantation process to introduce a plurality of atoms into the refractory metal layer. Moreover, the atoms introduced into the refractory metal layer include oxygen atoms, nitrogen atoms or a mixture of atoms comprising oxygen atoms and nitrogen atoms. Incidentally, the oxygen-containing implantation layer includes an oxygen-containing titanium nitride layer and the refractory metal layer is formed from titanium by deposition.
Because of the formation of the oxygen-containing implantation layer, the copper atoms of the patterned copper layer can be blocked by the oxygen-containing implantation layer. Additionally, the percentage of the oxygen atoms in the oxygen-containing implantation layer formed by the implantation process can be controlled. Therefore, the diffusion barrier efficacy of the oxygen-containing implantation nitride layer can be precisely controlled.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.